This invention relates to a master cylinder and more particularly, to a tandem-type master cylinder. There have been proposed and practically employed a variety of tandem-type master cylinders in the prior art. One of the prior art tandem-type master cylinders has an equalizing cylinder movably provided between the pressure generation chambers associated with the two pistons, respectively, in order to equalize pressure generated by the leading piston and following piston which are coaxially disposed within the main cylinder for slidable movement. This results in the pressure within the pressure chambers being adjusted to equalize the pressures. However, since the equalizing cylinder is designed to move back and forth within the main cylinder and since the movement of the equalizing cylinder is vibratory, prompt and precise, movement of the equalizing cylinder can not be expected. Since the equalizing cylinder moves in the two opposite directions or back and forth, the equalizing cylinder has to be maintained in its neutral position prior to the operation of the master cylinder and thus, for this purpose, the number of parts required for the device is inevitably increased which in turn increases the size of the device resulting in increase in the size of the entire master cylinder.
In order to eliminate the disadvantages inherent in the prior art master cylinder described above, the applicant herein describes a master cylinder such as disclosed in Japanese Patent Application No. 106061/1966. In the master cylinder as disclosed in this Japanese Patent application, prompt and precise operation of the equalizing cylinder is ensured and further, the number of parts of the equalizing cylinder is reduced, resulting in the reduction of the entire size of the master cylinder. However, in the master cylinder of the above noted patent application, as in the case of other tandem-type master cylinders known prior to this patent application, when the piston assembly comprising the smaller and larger diameter pistons is inserted into the main cylinder of the master cylinder, a sleeve and a spring are first inserted into the cylinder and the piston assembly is then inserted into the cylinder against the force of the spring. Such an assembling procedure is very inefficient in both the operation for inserting the piston assembly into the sleeve and cylinder or the assembling of the complete master cylinder because there is play present in the connection between the smaller and larger diameter positions.
Furthermore, in the master cylinder of the type as disclosed in the above noted patent application, in order to connect the larger and smaller diameter pistons together, it is necessary to employ a cylindrical split sleeve, a cylindrical retainer disposed about the split sleeve to protect the sleeve and a clip for preventing the retainer from coming off the sleeve in the axial direction. Thus, it is necessary to assemble the clip onto the sleeve and retainer assembly after the retainer has been disposed about the split sleeve in order to prevent the retainer from coming off the sleeve in the axial direction. This requirement increases the time and cost required to assemble the device.